1. Field of Invention
The invention relates generally to the hot rolling of steel strip. More particularly, the invention relates to apparatus for hot rolling steel strip in direct sequence with a continuous casting strip mold.
2. Summary of the Prior Art
The advantages of hot rolling steel strip in direct sequence with a continuous casting mold are well known in the art. To accomplish this objective, the strip issuing substantially vertically and downwardly from the casting mold must be diverted into a substantially horizontal plane and cut into predetermined lengths. Further, the strip must have a metallurgical structure which is as homogeneous as possible, and a uniform temperature profile along its length, across its width and through its thickness, when it enters the rolling mill. These requirements assure that the expansion of the area of the strip during rolling does not adversely effect the casting operation, and that the final product displays appropriate physical properties for its intended use.
Manufacturing lines for the production of hot rolled steel strip are known in the art. In such lines a mold is provided in which a steel melt is continuously cast such that strip issues from the mold cavity in a substantially vertical downward direction. As the strip leaves the mold, it enters a strip guiding device wherein it is diverted into a substantially horizontal plane by bending, guiding, driving, and straightening rollers. Thereafter, the strip enters a crosscutting device wherein it is cut into lengths for subsequent rolling. The lengths of cut strip then enter a straight temperature equalization furnace from which they are subsequently passed to the rolling mill. The rolling mill may be generally considered to include one or more press rolling devices, a cooling zone, and apparatus for coiling the rolled strip for storage and/or shipment.
One known crosscutting device includes a pair of shearing elements which coact in a scissors like manner to sever the strip transversely to its direction of travel. It is also known that a pair of press rolls may be located between the outlet of the mold and the inlet of the strip guiding device for the purpose of reducing the thickness of the strip prior to its passage through the remainder of the devices in the manufacturing line. Such initial rolling is advantageous in reducing the forces required to bend and cut the strip thereby reducing the wear upon, and the strength requirements of, the strip guiding device and the crosscutter. The expansion of the area of the strip in such initial rolling has been found to be small enough that casting operations are not seriously adversely effected.
It will be understood that known hot rolled steel strip manufacturing lines represent significant capital investments both in terms of the cost of the necessary equipment, and in terms of the cost of the manufacturing floor space required for the set-up and operation of that equipment. Further, since each of the equipment elements of the manufacturing line is separate from the others, significant thermal energy is lost during the passage of the strip from the mold to the temperature equalization furnace. This lose of thermal energy can lead to metallurgical errors in the final product rendering it either useless or unsuitable for its intended purpose.